B707 lap joint specimen No. 349 - NDI inspections
Bibliographic record
Abstract
Three lap joint sections taken from a B707 aircraft were initially inspected using x-ray inspection techniques to determine if corrosion pillowing cracks were present. Since numerous pillowing cracks were found in all three lap joints, four other nondestructive inspection (NDI) techniques were used to characterize the damage present in each joint. A visual inspection was first made to assess the damage present on the outer surfaces of each joint (both inboard and outboard skins). The NDI techniques that were used included multi frequency eddy current, pulsed eddy current, ultrasonic (C Scan) and D Sight™ inspections. The level of corrosion and corrosion pillowing that was present in these specimens was sufficient to cause a number of the rivet heads to “fail”. Some of the rivets had been replaced, probably during prior maintenance but had since failed due to the stress caused by the corrosion pillowing. There was also corrosion present on the inboard surface as well as on the stringers. The paint had not been stripped and there were no surface cracks visually apparent. The three specimens were separately inspected and all the results obtained are shown in the figures presented below. The eddy current inspections were carried out using four different frequencies 1.1 kHz, 2.4 kHz, 4.3 kHz and 9.6 kHz. Ultrasonic inspection was performed at a frequency of 15 MHz. The X-ray inspection displayed several cracks around the majority of the rivets. High beam energy levels were required to detect pillowing cracks in the intact joint and resulted in extremely dark images thus only one X-ray image, from 349B, is shown in this report. From all of the x-ray inspections the areas indicated to have significant pillowing cracks are noted on the schematic of each specimen.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.008 | 0.003 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".